If you have any sort of notion that a bull and cow share loving glances and intimate moments in the field, resulting some nine months later in the birth of a calf, then you had better think again. Reproduction in bovine is not romantic but high-tech – and the development is moving forward by leaps and bounds. This is especially the case in Brazil where over 350,000 fertilized embryos are transferred to recipient cows every year.

Brazilians are heavy users of the latest technology, but have so far not been able to fully optimize the process in all areas. This will be remedied in a new project in which scientists from Denmark and Brazil work together to improve reproductive technology, among other things by the use of genetic tools.

Scientists from Aarhus University are also participating in the project which is managed by the University of Copenhagen and São Paulo State University. Additional participants include São Paulo University and the Brazilian company Vitrogen. The four-year project has a budget of 10.5 million DKK, of which The Danish Council for Strategic Research has funded 6.1 million.

New life created in the lab

In the modern production of milk and beef the cow and bull never meet. Instead reproduction is taken over by modern technology. A common technique has been to fertilize cows with semen from a bull using artificial insemination. The fertilized eggs divide and become small embryos (foetuses). After a few days, when the embryos have evolved into so-called blastocysts, they are collected from the donor cow and transferred into suitable recipient cows.

The technology has recently advanced to such an extent that eggs can now be collected from the donor cow already at the unfertilized stage. This technique is called "ovum pick-up" (OPU). The eggs are matured in the laboratory, where they are fertilized and then cultured for six days. They have then reached the blastocyst stage, at which point they are transferred to the recipient cows. This part of the process is called "in-vitro production” (IVP).

With the new technique both fertilization and maturation to blastocysts take place in the test tube instead of in the donor cow. It is this process, the combination of OPU and IVP, that the Brazilians are skilled and experienced in performing. But there is room for improvement – and it is here that scientists from Aarhus University can help.

Genetics supporting technology

The project aims to build bridges between the embryo technology and genetic techniques by focusing on the underlying biological mechanisms, identifying key genes and genetic markers and develop programs to select the best donors and recipients.

The Danish scientists will study the genetic elements, with the aim of identifying the most suitable bovine donors of unfertilized eggs. They will similarly examine the genetic factors and markers to identify the most suitable recipient cows for blastocysts. They will also be looking for ways to improve the in-vitro production, i.e. the part of the process taking place in the laboratory.

The study is based on two species of beef and dairy cattle. One is Bos taurus, which is the common European species. The second is Bos indicus, also known as zebu, which is a tropical species. As the studies are conducted in both Denmark and Brazil, it includes both tropical and temperate climates, and with two types of environments and two species of cattle the results are widely applicable to many parts of the world.

- With over 350,000 transfers of fertilized eggs per year, the Brazilians have enormous data material and practical experience and routine. It gives a mighty good starting point for carrying out genetic studies and performing practical tests, says one of the project scientists, professor Henrik Callesen from the Department of Animal Science at Aarhus University.

For further information please contct: Professor Henrik Callesen, Department of Animal Science, e-mail: henrik.callesen@agrsci.dk, telephone: +45 8715 7989, mobile: +45 2080 3435